Plasma Ball Explanation

A plasma ball in action.

Plasma balls are globes that light up with streamers of plasma from the center radiating out to the edge of the glass globe. They can be found at almost any novelty shop as well as several locations online. Besides simply looking neat, they also show off some physics as well.

Definition of a Plasma Ball

A plasma ball is a glass globe filled with low pressure gases such as neon, argon or xenon. An electrode is placed in the center of the globe and connected to the power supply which gives a high-voltage, high frequency, alternating current.

History

Initially developed and patented by Nikola Tesla (called the "Inert Gas Discharge Tube"), the modern-day version of the plasma ball was designed in the 1970's by an MIT student named Bill Parker. Tesla was studying the effects of high frequency current discharged into low-pressure gases contained by a gas tube.

How Does It Work?

According to PowerLabs, plasma, often defined as "the fourth state of matter," is "a hot ionized gas." Simply stated, a plasma is a gas containing charged particles like electrons and ions.

The application of the initial voltage through the power supply creates a second oscillating voltage on the electrode. This creates an alternative electromagnetic field that keeps the free electrons moving around inside. As the electrons get enough energy to break loose from the center electrode, they accelerate due to the electromagnetic field and gain energy. The plasma streamer is created as the electrons move around and ionize the gas. The light that emanates from a plasma stream is the excess energy from the atoms returning to a lower energy state from an excited state. The color of the light depends upon the gas inside the globe.

Sample Experiments

An easy experiment to do when near a plasma ball is to place your hand on the glass. Touching the glass will alter the electric field of the plasma ball and cause a single plasma stream to extend from the center electrode to the point where your hand is touching it.

Another easy experiment is to hold a fluorescent light bulb near a plasma ball. The electric field surrounding the ball is strong enough to excite the mercury gas inside the bulb and will cause the bulb to glow.

Warnings and Considerations

While plasma balls can be fun to watch and to experiment with, anyone with a heart condition or a pacemaker should not touch one. Plasma balls create their own electric fields around them and therefore should be kept away from anything that might be affected by an electric field such as computers, cell phones and other digital devices.

References

• Softpedia: How Do Plasma Lamps Work?
• PowerLabs: Plasma Globe Page
• The Plasma Ball Page

Resources

• Read this Article in Spanish